International Space Station managers welcome the return of a U.S. re-supply capability that regular SpaceX Falcon 9/Dragon operations promise, Mike Suffredini, NASA's ISS program manager, told a news briefing on the eve of the Hawthorne, Calif., based company's scheduled CRS-1 launching.
That capability has been absent since the final shuttle mission in July 2011.
The first of a dozen deliveries to the station by Hawthorne, Calif., based SpaceX under NASA's $1.6 billion Commercial Resupply Services agreement is scheduled to lift off from Cape Canaveral Air Force Station, Fla., on Sunday at 8:35 p.m., EDT.
Weather could be a factor, as a fall front moves leisurely through Central Florida, limiting the prospects for favorable conditions to 60 percent.
Dragon, top, docked to ISS during May demonstration flight. Image Credit: NASA
Like the shuttle, Dragon is designed to return as well as deliver cargo to the ISS. Russia's Progress, the European Space Agency's Automated Transfer Vehicle and Japan's H-II Transfer Vehicle all do not feature a return capability.
"It's nice to have a U.S. indigenous capability, and one of the main reasons is the flexibility to get hardware to the ISS," said Suffredini.
SpaceX's emergence in the shuttle's aftermath made it possible to advance the scheduled delivery of a pump for the station's waste handling system from an April 2013 ATV flight to the CRS-1 delivery. Dragon is also scheduled to return from its three week flight with nearly 500 containers of frozen urine and blood specimens that have accumulated on the station since the last visit by a shuttle crew.
The specimens will be studied by medical experts to assess changes in the metabolism of astronauts assigned to long duration missions.
"When you have a launch vehicle in your country it makes it a lot easier because shipping and customs regulations can kill you, when you are trying to get overseas," said Suffredini. "This really makes the process faster."
With a lift off late Sunday, the unpiloted Dragon would rendezvous with the space station early Wednesday. Japanese astronaut Akihiko Hoshide and station commander Sunita Williams, of NASA, will be posted in the Cupola observation deck at the controls of the Canadian robot arm. As Dragon moves in range of the outstretched 58-foot-long robot arm, the two astronauts will grapple the freighter and berth it to the station's U. S. segment.
The capsule is carrying nearly 1,000 pounds of supplies and research gear.
Dragon will remain berthed until Oct. 28. The mission plan calls for the capsule to depart and re-enter the Earth's atmosphere on the same day, descending by parachute into the Pacific Ocean off the southern California coast, where recovery ships will be waiting.
Dragon's return manifest includes just over 1,200 pounds of science samples as well as station hardware awaiting refurbishment and an opportunity to return to the orbiting science lab.
Dragon demonstrated its ISS cargo capabilities in May, with a successful demonstration mission conducted as part of NASA's Commercial Orbital Transportation Systems program.
The COTS demo qualified SpaceX to begin regular cargo operations under the NASA Commercial Resupply Services agreement signed in December 2008 and effective through 2015.